Inlet and outlet baffle structure for sewage treatment tanks

ABSTRACT

This application discloses a septic tank construction including an inlet baffle structure and an outlet baffle structure for reducing the turbulence in the liquid or clear zone of the septic tank. The tank has oppositely disposed arcuate end walls which bow outward. In one of the end walls is an inlet for receiving incoming raw sewage. Connected with the inlet is an inlet baffle structure for introducing the incoming sewage into the fluids in the tank with a minimum of turbulence. The inlet baffle structure comprises a generally tubular structure which is connected with the inlet and terminates in a fluid introducing flared opening disposed toward the end wall. The fluid introducing opening is oval in cross section with its major axis extending vertically. In the other end wall is an outlet for discharging treated fluids to the disposal field. An outlet baffle structure for receiving treated fluids to be discharged is connected with the outlet. The outlet baffle structure comprises a tubular structure which is connected with the outlet and which terminates in a flared fluid receiving opening disposed toward the end wall. The fluid receiving opening is oval in cross section with its minor axis extending vertically.

BACKGROUND OF THE INVENTION

This application relates to the art of sewage treatment and moreparticularly to inlet and outlet baffle structures for use inconjunction with septic and other sewage treatment tanks. The inventionfinds particular utility in conjunction with molded plastic tanks havingarcuate end walls and will be described with reference thereto. It willbe appreciated, however, that the invention finds application in othertreatment tanks which are constructed of concrete, concrete block,plastic, metal, and other materials and which are configured inrectangular prisms, cylinders, spheres, and other shapes.

Most commonly, the inlet and outlet baffles of septic tanks comprisegenerally T-shaped structures. Specifically, the stem of the T connectswith the horizontal inlet or outlet pipe. The cross bar of the Tcommonly extends into the air space at the top of the tank to act as avent and extends below the scum layer into the liquid or clear zone ofthe tank. The inlet baffle functions to drop the incoming sewagedirectly in the liquid or clear zone of the sewage treatment tank. Theoutlet baffle functions to block the scum from being discharged into thedisposal field. Rather, liquids from the liquid or clear zone of theseptic tank are drawn off by the outlet baffle for distribution throughthe disposal field.

It has been recognized that the gas bubble rising in the liquid or clearzone of the septic tank should be prevented from entering the outletbaffle to reduce the flow of suspended solids into the absorption fieldand slow soil pore clogging. This has been achieved by disposing adeflector below the outlet Tee, by fastening a special outlet boxprojecting outward from the side of the septic tank wall, or the like.

One of the problems with the prior art septic tank structures has beenthe turbulence in the liquid or clear zone caused by the entrance ofincoming sewage and the discharge of treated fluids. Such turbulencetends to interfere with the normal settling of sludge from the liquid inthe clear zone. The turbulence tends to hold particles suspended in theliquid.

Further the turbulence and relative placement of the inlet and outletbaffles have tended to allow shortcircuiting of raw sewage from theinlet directly to the outlet baffle. In shortcircuiting, raw orpartially treated sewage is discharged into the distribution system tooquickly for the anaerobic bacteria in the clear zone of the septic tankto treat it properly and for settling to occur.

SUMMARY OF THE INVENTION

The present invention provides new and improved inlet and outlet bafflestructures which overcome the above-referenced problems and others yetprovide a treatment system which is simple, economical, and effective.

In accordance with the present invention, there is provided a sewagetreatment construction for minimizing fluid turbulence from the ingressof incoming sewage and the egress of treated and settled fluids. Theconstruction comprises a tank for holding sewage for treatment whichincludes a first end wall having an inlet for receiving the incomingsewage and a second end wall having an outlet for discharging thetreated and settled fluids. The construction further comprises an inletbaffle structure for introducing incoming sewage into the tank. Theinlet baffle structure comprises a first generally tubular structurewhich is in fluid connection with the inlet and which defines a fluidintroducing opening through which incoming sewage is introduced into thetank. The fluid introducing opening is disposed substantially in avertical plane. The construction further comprises an outlet bafflestructure for receiving treated fluid to be discharged from the tankthrough the outlet. The outlet baffle structure comprises a generallytubular structure which is in fluid connection with the outlet and whichdefines a fluid receiving opening through which treated and settledfluids are received for discharge from the tank. The fluid receivingopening is disposed substantially in a vertical plane. The fluidintroducing opening and the fluid receiving opening face generally awayfrom each other.

In accordance with another aspect of the invention, there is provided abaffle construction for reducing turbulence in fluids in a sewagetreatment tank. The baffle structure comprises a first generally tubularportion having a coupling at one end. The coupling is adapted toconnection with an inlet or outlet of a sewage treatment tank. Thebaffle structure further comprises a second generally tubular portionwhich has a vent at one end. The second generally tubular portion is influid connection with the other end of the first generally tubularportion. The baffle structure further comprises a third generallytubular portion which defines an opening at one end. The third generallytubular portion is divergent from a first relatively small cross sectionadjacent said second generally tubular portion to a second relativelylarge cross section adjacent the opening. The baffle structure furthercomprises a transition zone for providing fluid connection between theother end of the second generally tubular portion and the other end ofthe third generally tubular portion.

A principle advantage of the invention is that it promotes tranquilityin the liquid or clear zone and reduces turbulence of the liquid phasesof the sewage treatment. The invention is advantageous in that itreduces the ingress velocity of incoming sewage and the egress velocityof treated and settled fluids.

Another advantage of the present invention is that it inhibits gasesfrom entering the inlet and outlet conduits thus reducing suspendedsolids escaping on ascending gas bubbles.

Yet another advantage of the present invention is that it inhibitsshortcircuiting of raw sewage directly from the inlet baffle to theoutlet baffle.

BRIEF DESCRIPTION OF THE FIGURES

The drawings are for the purpose of illustrating a preferred embodimentof the invention only. They are not to be construed as limiting thescope of the invention.

FIG. 1 is a vertical cross section of a septic tank construction incombination with inlet and outlet baffle structure in accordance withthe present invention;

FIGS. 2A, B, and C are side, end, and top plan views, respectively, ofthe inlet baffle structure of FIG. 1;

FIGS. 3A, B, and C are side, end, and top plan views, respectively, ofthe outlet baffle structure of FIG. 1;

FIG. 4 is a vertical cross section of a septic tank construction incombination with an alternate embodiment of the present invention; and

FIG. 5 is a perspective view of an alternate embodiment of a baffle inaccordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIG. 1, the figure shows a septic or other sewagetreatment tank A in combination with an inlet baffle structure B and anoutlet baffle structure C. Raw sewage is received by the inlet bafflestructure B which introduces it gently into the liquid or clear zone ofthe septic tank. Anaerobic bacteria in the liquid zone digest the rawsewage. During the anaerobic digestion process, solids settle and aredeposited in a sludge layer at the bottom of the septic tank and lightersewage components, such as grease, float through the liquid zone to forma layer of scum. Gas bubbles given off during the anaerobic digestion,also rise to the top of the liquid zone. The gas bubbles frequently liftsmall suspended particles. When incoming sewage is received, the liquidlevel in the tank rises. When the liquid level exceeds the level of theoutlet, treated and settled fluids, i.e. fluids which have depositedmost of the larger suspended solids, are forced by gravity through theoutlet baffle to a disposal field.

The septic tank A comprises a first arcuate end wall 10 which bowsoutward in a generally domelike configuration. At the opposite end ofthe tank is a second arcuate end wall 12 which also bows outward in agenerally domelike configuration. In the preferred embodiment, the endwalls are corrugated, spherical segments. Between the arcuate end walls10 and 12, a corrugated central section 14 is disposed. The corrugatedcentral section 14 comprises a generally large radius of curvaturecorrugated bottom wall and a pair of arcuate corrugated side walls whichextend from the bottom wall and meet at an apex area.

Disposed in the first arcuate end wall 10 is an inlet 20 which isdefined by an annular collar 22. The annular collar 22 is disposed in arecessed indentation area 24 of the first end wall 10 which is recessedinward. The indentation area protects the inlet and connections with theinlet from impact during shipping and handling and from settling andother forces after subterranean installation. The indentation areaincludes a sloping bottom wall 26 and a back wall 28. The bottom walland back walls connect with the arcuate first end wall 10 and with eachother. The inlet annular collar 22 is integrally formed with the backwall 28. A pair of side walls, of which side wall 30 is shown in thedrawings, is connected between the arcuate first end wall 10, bottomwall 26, and back wall 28. A spigot or tubing section 32 extends throughannular collar 22. An O-ring 34 provides a fluid seal between spigot 32and annular collar 22. The spigot has a bell coupling 36 at one end forreceiving a sewage line. The inlet baffle B is secured to the other end.The spigot 32 is longer than collar 22 to enable the spigot to movelongitudinally through the annular collar if the septic tank A or thesewage line should expand, contract, settle, or the like.

Disposed in the second arcuate end wall 12 is an outlet 40. The outlet40 is defined by an annular outlet collar 42 which projects toward theinterior of the tank A. The outlet, like the inlet, is disposed in anindentation area 44 which is recessed from the second arcuate end wall12 toward the interior of the tank. This protects the outlet andconnection with the outlet during shipping and installation as well asafter its subterranean installation. The recessed indentation area isdefined by a gently sloping bottom wall 46, a back wall 48, and a pairof side walls, of which side wall 50 is shown in FIG. 1. An outletspigot or tubing section 52 extends through annular collar 42. An O-ring54 provides a fluid seal between spigot 52 and the annular collar 42.The spigot 52 has a bell coupling 56 at one end for connection with anoutlet line to the distribution field. The outlet baffle C is connectedwith the other end of spigot 52. The spigot is longer than annularcollar 42 to permit relative longitudinal movement between the spigotand the annular collar.

With reference now to FIGS. 1 and 2, the inlet baffle structure B has afirst generally tubular portion 60. The tubular portion 60 has acoupling 62 at one end which is adapted to be received on the inletspigot 32. The other end 64 of the first tubular portion 60 is connectedwith a second generally tubular portion 70. The second tubular portion70 has a vent aperture disposed at one end 72. A third generally tubularportion 80 defines an elongated opening 82 at one end for introducingfluid and sewage materials into the tank. A transition zone 84 providesa fluid connection between the other end 74 of the second tubularportion 70 and the other end 86 of the third generally tubular portion80.

The cross section of the first generally tubular portion 60 and thecoupling 62 in a first generally vertical plane is circular. The crosssection of the second generally tubular portion 70 is similarlycircular. The third generally tubular portion is divergent from a firstrelatively smaller circular cross section adjacent the second generallytubular portion to a second relatively larger oval cross sectionadjacent the opening 82. The fluid introducing opening 82 which isdefined by the one end of the third generally tubular portion 80 isgenerally oval and has a major axis 90 extending in the verticaldirection and a minor axis 92 extending in the horizontal direction. Thedimension of the major axis 90 in the vertical direction is about 8inches and the dimension of the minor axis 92 in the horizontaldirection is about 41/2 inches. Thus the major axis is about 11/2 to 2times the minor axis. The dimension of the diameter of the first andsecond generally tubular portions is substantially the same as thedimension of the minor axis. It is contemplated that the cross sectionof the generally tubular portions may be other than circular such assquare, rectangular, or the like. Similarly, the elongated fluidintroducing opening 82 may be rectangular, square, triangular, ovoid,semicircular, or the like.

Further in the preferred embodiment, the first generally tubular portion60 extends along a first substantially horizontal axis 94, the secondgenerally tubular portion 70 extends along a second axis 96 and saidthird generally tubular portion 80 extends along a third axis 98. Thesecond axis 96 and the third axis 98 are disposed at an angle ofgenerally 130 to 155 degrees. Specific to the preferred embodiment, theangle is 1431/2 degrees. The first axis 94, the second axis 96, and thethird axis 98 are substantially coplanar in a common inlet plane. Theelongated fluid introducing opening 82 is disposed in a second planewhich is parallel to the cross section of the first tubing portion 60 orcoupling 62. The major axis 90 of the elongated fluid introducingopening is parallel with the second axis 96 and lies in the common inletplane of the first, second and third axis. The minor axis 92 isperpendicular to the major axis 96 and the common inlet plane. The fluidintroducing opening is disposed farther from the second axis 96 than iscoupling 62. This brings the fluid introducing opening closer to thefirst arcuate end wall 10. Also disposed in the common inlet plane is arecessed central valley portion of the corrugations in the first endwall 10. The valley portion is generally triangular in cross section.Incoming raw sewage is received in the first tubular portion 60 anddrops vertically through the second tubular portion 70. The sewage isslowed by the lower surface of the third tubular portion 80 whichabsorbs some of its kinetic energy and reduces its velocity. Theenlarged, diverging third tubular portion 80 and the fluid introducingopening 82 further reduce the entrance velocity of the sewage. Thesewage with the reduced velocity is discharged from fluid introducingopening 82 generally toward the first arcuate side wall 10. The centralvalley portion deflects peripherally any component of the velocity whichreaches it. The reduced velocity and directing the velocity componentoutward toward the end wall of the tank reduces the turbulence in theliquid or clear zone. The inward recess of the inlet 20, and the outwardarcuate side wall 10 cooperate to dispose the fluid introducing opening82 sufficiently distant from the end wall 10 that incoming sewage may bedischarged toward the side wall without clogging or detrimentalinteractions. Discharging the incoming sewage toward the arcuate endwall not only decreases the turbulence but also reduces the tendency forincoming sewage materials to reach the outlet before being fullytreated. If the third axis 98 were disposed more horizontally, morekinetic energy from the incoming sewage materials would be absorbed, butthe tendency for the sewage materials to clog the third tubular section80 would be increased. Disposing the third axis at about 361/2 degreesto the vertical enables the third section to absorb a large component ofthe kinetic energy of the incoming sewage without a substantial tendencyfor the third tubular section to become clogged.

With reference now to FIGS. 1 and 3, the outlet baffle structurecomprises a first generally tubular portion 100. The first tubularportion 100 has a coupling 102 at one end which is adapted to bereceived on the spigot 52. The first tubular portion 100 is connected atits other end 104 with a second generally tubular portion 110. Thesecond tubular portion 110 has a vent aperture 112 at one end. A thirdgenerally tubular portion 120 defines an elongated opening 122 at oneend for receiving treated fluid. The third generally tubular portion 120is divergent from a first relatively smaller cross section adjacent thesecond generally tubular portion 110 to a second relatively larger crosssection adjacent the fluid receiving opening 122. The enlarged crosssection at the fluid receiving opening reduces the egress velocity ofreceived fluids at the opening. A transition zone 124 provides a fluidconnection between the other end 114 of the second tubular portion 110and the other end 126 of the third tubular portion 120.

The first tubular portion 100 extends along a first axis 130. Wheninstalled in the septic tank A, the first axis 130 is disposedsubstantially horizontally. The second tubular portion 110 extends alonga second axis 132. The third tubular portion 120 extends along asubstantially circular arc segment 134. The first axis 130 is disposedsubstantially perpendicular to the second axis 132. The first axis 130,the second axis 132, and the circular arc segment 134 are disposed in acommon outlet plane. When installed in the tank, the common outlet planeis substantially vertical and coplanar with the common inlet plane.

In the preferred embodiment the cross section of the first tubularsection 100 and coupling 102 in a first substantially vertical plane issubstantially circular. Similarly, the cross section of the secondtubular portion 110 is circular. The cross section of the elongatedfluid receiving opening 122 in a second substantially vertical plane issubstantially oval. The third generally tubular portion is divergentfrom a generally circular cross section adjacent the second generallytubular portion to a generally oval cross section adjacent the fluidreceiving opening. The oval has a major axis 140 which is disposedperpendicular to the common outlet plane and a minor axis 142 which isdisposed in the common outlet plane and substantially parallel to thesecond axis 132. The fluid receiving opening 122 is disposed fartherfrom the second axes 132 than is coupling 102. This places the fluidreceiving opening 122 closer to the second end wall 12 of the tank. Itis contemplated, however, that other cross sections such as square,rectangular, octagonal and the like may be used for the cross sectionsof the first tubular portion 100, the second tubular portion 112 and thefluid receiving opening 122. In the preferred embodiment, the major axisis 7 inches long and the minor axis is about 31/2 inches. It ispreferred that the major axis be about twice the dimension of the minoraxis.

When sewage is introduced into the tank, the level of liquid in theliquid or clear zone is raised. The force of gravity on the liquid inthe clear zone forces liquid through the outlet baffle structure untilthe level of the liquid reaches the level of the bottom of outlet 40.Because the fluid receiving opening is enlarged, the velocity of thedischarged fluid is less at the fluid receiving opening than in thefirst and second generally tubular portions and the outlet line to thedistribution field which are smaller in cross section. The size andorientation of the fluid receiving opening reduces the amount ofturbulence caused by fluid being received by the outlet baffle. Furtherdisposing the fluid receiving outlet 122 vertically in addition tohelping reduce turbulence, also inhibits the outlet baffle fromreceiving rising gas bubbles released by the anaerobic bacteria.

FIG. 4 illustrates an alternate embodiment in which the presentinvention is utilized in conjunction with a rectangular prism shapedseptic tank. In FIG. 4, like elements are indicated with the samereference numeral as the corresponding element of FIGS. 1-3 followed bya prime ('). An inlet opening 20' which is defined by a length of tubingis disposed in a first side wall 10' of the septic tank A'. Withreference also to FIG. 2C, a first tubular portion 60' of the inletbaffle is connected with the inlet length of tubing. The first tubularportion 60' extends along a first generally horizontal axis. A secondgenerally tubular portion 70' is connected with the end of the firstgenerally tubular portion 60'. The second tubular portion extends alonga second vertical axis which is perpendicular to the first axis. Atransition zone 84' connects the second tubular portion 70' with a thirdtubular portion 80'. The third tubular portion terminates in a fluidintroducing opening 82'. The third tubular portion 80' is divergent froma relatively smaller cross section adjacent the transition zone 84' to arelatively larger cross section adjacent the fluid introducing opening82'. The third tubular portion extends along a third axis. The secondand third axes lie in a common plane which is perpendicular to the firstaxis. This orients the fluid introducing opening 82' facing toward aside wall of the septic tank.

An outlet opening 40' which is defined by a length of tubing is disposedin a second side wall 12' of the septic tank. Also with reference alsoto FIG. 3C, the inlet baffle has a first generally tubular portion 100'which is connected with the outlet tubing length. The first generallytubular portion 100 extends along a first axis. Connected with one endof the first generally tubular portion is a second generally tubularportion 110' extending along a second axis. The first and second axisare substantially perpendicular to each other. Connecting the secondtubular section 110' with a third generally tubular section 120' is atransition zone 124'. The third generally tubular portion 120' extendsalong a generally circular arc segment. The second and third generallytubular portions lie in a common plane which is substantiallyperpendicular to the first axes. The third generally tubular portion120' terminates in a fluid receiving opening which is disposed facingtoward the opposite side wall of the septic tank than fluid introducingopening 82'. The fluid introducing opening and the fluid receivingopening thus face away from each other, specifically they are offsetrelative to each other by 180 degrees. It is contemplated that the fluidintroducing opening and the fluid receiving opening may face away fromeach other by less than 180 degrees. For example, the fluid introducingopening and the fluid receiving opening may be rotated 45 degrees towardthe center of the tank. This causes the fluid introducing opening andthe fluid receiving opening to be offset relative to each other by about90 degrees. Alternately the fluid introducing opening and the fluidreceiving opening could both be rotated toward their respective endwalls of the septic tank by about 45 degrees causing the openings to beoffset relative to each other by about 180 degrees. It is readilyapparent that various other orientations of the fluid introducingopening and fluid receiving opening may be selected in accordance withthe present invention.

FIG. 5 illustrates a general purpose baffle for use as an inlet or anoutlet baffle. The baffle has a first generally tubular portion 150which has an elongated coupling 152 at one end which is adapted to beconnected to a conventional four inch circular pipe. The other end isflared downward at 154 for a smoother fluid flow transition into asecond generally tubular portion 160. The second generally tubularportion tapers at the top end to a vent opening 162. At its other end,the second generally tubular portion is in fluid connection with a thirdgenerally tubular portion 170. The fluid connection between the secondand third generally tubular portions may be referenced as a transitionzone. The third generally tubular portion is divergent from a relativelysmall cross section, such as a four inch square cross section, adjacentthe second generally tubular portion to a relatively large crosssection, such as an eight inch square cross section, adjacent its otherend. The other end defines an enlarged opening 172. The opening 172 isdisposed in a vertical plane which is offset from the coupling 152 byabout 45 degrees. When a pair of these baffles are installed on parallelinlet and outlet pipes, the two openings are offset by 180 degreesrelative to each other. A brace 174 is connected with the thirdgenerally tubular portion for fixing the minimum distance between theopening 172 and the side wall of the tank. Means, such as ribs 176, aredisposed projecting into the second and third generally tubular portionsfor further slowing the fluid velocity. The ribs also strengthen thebaffle structure. The first generally tubular portion extends along afirst generally horizontal axis. The second generally tubular portionextends along a second axis which may be linear or arcuate. The secondaxis slopes a small amount from vertical generally toward the enlargedopening 172. The third generally tubular portion extends along a thirdarcuate axis.

The invention has been described with reference to the preferredembodiment. Obviously modifications and alterations will occur to othersupon the reading and understanding of the specifications. It is ourintention to include all such modifications and alterations insofar asthey come within the scope of the appended claims or the equivalentsthereof.

We claim:
 1. A sewage treatment construction for minimizing fluidturbulence from the ingress of incoming sewage, the constructioncomprising:(a) a tank for holding sewage for treatment, said tankincluding a first end wall which includes an inlet for receivingincoming sewage and a second end wall which includes an outlet fordischarging treated fluids; (b) an inlet baffle structure forintroducing incoming sewage into the tank, said inlet baffle structurecomprising:(i) a first generally tubular portion which is operativelyconnected at one end with said inlet; (ii) a second generally tubularportion having a vent aperture adjacent one end, the second generallytubular portion being in fluid connection with the other end of saidfirst generally tubular portion; (iii) a third generally tubular portiondefining a fluid introducing opening at one end through which incomingsewage is introduced into the tank, the third tubular portion divergingtoward the fluid introducing opening such that the flow rate of incomingsewage tends to be slowed as it approaches the fluid introducingopening, whereby turbulence in the tank is reduced; and (iv) atransition zone providing fluid connection between the other end of saidsecond generally tubular portion and the other end of said thirdgenerally tubular portion; (c) an outlet baffle structure for receivingtreated fluid to be discharged from the tank through said outlet, saidoutlet baffle structure comprising a second generally tubular structurewhich is in fluid connection with said outlet and which defines a fluidreceiving opening through which treated fluids are received fordischarge from said tank.
 2. The construction as set forth in claim 1wherein said first generally tubular portion extends along a first axis,said second generally tubular portion extends along a second axis andsaid third generally tubular portion extends generally along a thirdaxis, at least said second and third axes being generally coplanar. 3.The construction as set forth in claim 2 wherein said first and secondaxes are substantially perpendicular and wherein said second and thirdaxes are disposed at an angle of generally 135 degrees to 155 degrees toeach other.
 4. The construction as set forth in claim 2 wherein thefirst and second generally tubular portions are generally circular incross section and wherein said third generally tubular portion isdivergent from a generally circular cross section adjacent said secondgenerally tubular portion to a generally oval cross section adjacentsaid fluid introducing opening, said fluid introducing opening beinggenerally oval with a major axis which is substantially vertical.
 5. Asewage treatment construction for minimizing fluid turbulence from theegress of treated fluids, the construction comprising:(a) a tank forholding sewage for treatment, said tank including a first end wall whichhas an inlet for receiving incoming sewage and a second end wall whichhas an outlet for discharging treated fluids; (b) an inlet bafflestructure for introducing incoming sewage into the tank, said inletbaffle structure comprising a first generally tubular structure which isin fluid connection with said inlet and which incoming sewage isintroduced into said tank; (c) an outlet baffle structure for receivingtreated fluid to be discharged from the tank through said outlet, saidoutlet baffle structure comprises:(i) a first generally tubular portionwhich is in fluid connection at one end with said outlet; (ii) a secondgenerally tubular portion having a vent aperture adjacent one end, thesecond generally tubular portion being in fluid connection with theother end of the first generally tubular portion; (iii) a thirdgenerally tubular portion defining a fluid receiving opening at one endthrough which treated fluid are received for discharge through theoutlet, the third generally tubular portion being convergent from thefluid receiving opening toward the outlet whereby the convergence tendsto reduce the velocity at which treated fluids are received, the fluidreceiving opening being disposed substantially in a vertical plane suchthat suspended solids carried by ascending gas bubbles tend to pass bythe fluid receiving opening without being received in the outlet bafflestructure; and (iv) a transition zone providing fluid connection betweenthe other end of said second generally tubular portion and the other endof said third generally tubular portion.
 6. The construction as setforth in claim 5 wherein said first generally tubular portion extendsalong a first axis, said second generally tubular portion extends alonga second axis and said third generally tubular portion extends along anarc segment.
 7. The construction as set forth in claim 6 wherein saidfirst and second axes are substantially perpendicular.
 8. Theconstruction as set forth in claim 5 wherein the first and secondgenerally tubular portions are generally circular in cross section andwherein said third generally tubular portion is divergent from agenerally circular cross section adjacent said second generally tubularportion to a generally oval cross section adjacent said fluid receivingopening, said fluid receiving opening being generally oval with a minoraxis which is substantially vertical. .Iadd.
 9. A sewage treatmentconstruction for minimizing fluid turbulence from the ingress ofincoming sewage, the construction comprising:(a) a tank for holdingsewage for treatment, said tank including a first end wall whichincludes an inlet for receiving incoming sewage and a second end wallwhich includes an outlet for discharging treated fluids; (b) an inletstructure for introducing incoming sewage into the tank, said inletstructure comprising:(i) a first generally tubular portion which isoperatively connected at one end with said inlet; (ii) a secondgenerally tubular portion having a vent aperture adjacent one end, thesecond generally tubular portion being in fluid connection with theother end of said first generally tubular portion; (iii) a thirdgenerally tubular portion defining a fluid introducing opening at oneend through which incoming sewage is introduced into the tank, the thirdtubular portion diverging toward the fluid introducing opening such thatthe flow rate of incoming sewage tends to be slowed as it approaches thefluid introducing opening, whereby turbulence in the tank is reduced;and (iv) a transition zone providing fluid connection between the otherend of said second generally tubular portion and the other end of saidthird generally tubular portion; (c) an outlet structure for receivingtreated fluid to be discharged from the tank through said outlet, saidoutlet structure comprising a second generally tubular structure whichis in fluid connection with said outlet and which defines a fluidreceiving opening through which treated fluids are received fordischarge from said tank..Iaddend. .Iadd.10. A sewage treatmentconstruction for minimizing fluid turbulence from the egress of treatedfluids, the construction comprising: (a) a tank for holding sewage fortreatment, said tank including a first end wall which has an inlet forreceiving incoming sewage and a second end wall which has an outlet fordischarging treated fluids; (b) an inlet structure for introducingincoming sewage into the tank, said inlet structure comprising a firstgenerally tubular structure which is in fluid connection with said inletthrough which incoming sewage is introduced into said tank; (c) anoutlet structure for receiving treated fluid to be discharged from thetank through said outlet, said outlet structure comprises:(i) a firstgenerally tubular portion which is in fluid connection at one end withsaid outlet; (ii) a second generally tubular portion having a ventaperture adjacent one end, the second generally tubular portion being influid connection with the other end of the first generally tubularportion; (iii) a third generally tubular portion defining a fluidreceiving opening at one end through which treated fluid is received fordischarge through the outlet, the third generally tubular portion beingconvergent from the fluid receiving opening toward the outlet wherebythe convergence tends to reduce the velocity at which treated fluids arereceived, the fluid receiving opening being disposed substantially in avertical plane such that suspended solids carried by ascending gasbubbles tend to pass by the fluid receiving opening without beingreceived in the outlet structure; and (iv) a transition zone providingfluid connection between the other end of said second generally tubularportion and the other end of said third generally tubularportion..Iaddend.